Glime, J. M. 2017. Gardening: Horticultural Uses. Chapt. 7-1. In: Glime, J. M. Bryophyte Ecology. Volume 5. Uses. Ebook 7-1-1 sponsored by Michigan Technological University and the International Association of Bryologists. Last updated 11 October 2017 and available at
CHAPTER 7-1 GARDENING: HORTICULTURAL USES
TABLE OF CONTENTS
Horticultural Uses ...... 7-1-2 Shipping and Protecting...... 7-1-3 Soil Conditioning...... 7-1-3 Air Layering...... 7-1-8 Pot Culture...... 7-1-10 Potting Medium ...... 7-1-11 Dangers of Peat Culturing...... 7-1-12 Covering Pot Soil...... 7-1-13 Culturing Mushrooms and Other Fungi...... 7-1-13 Reforestation...... 7-1-14 Container Gardens...... 7-1-16 Bonkei...... 7-1-18 Dish Gardens...... 7-1-19 Bonsai...... 7-1-21 Hanging Baskets...... 7-1-23 Terraria...... 7-1-23 Bryophytes as Pests...... 7-1-28 Summary ...... 7-1-29 Acknowledgments...... 7-1-30 Literature Cited ...... 7-1-30
7-1-2 Chapter 7-1: Gardening: Horticultural Uses
CHAPTER 7-1 GARDENING: HORTICULTURAL USES
Figure 1. Sphagnum species such as this S. russowii are commonly used in horticulture as bedding material. Photo by Michael Lüth.
Horticultural Uses I was surprised that in my search for moss uses in peat moss as an amendment for clay soils, whereas animal horticulture I stumbled on a patent for culturing "moss dung was used for sandy soils (Raviv et al. 1986). Since seedlings" (Hiraoka 1995). The patent was to culture then, the need to keep plants alive during transfer made mosses that could henceforth be transplanted and grown in bryophytes a desirable medium because of their ability to a nursery. Hiraoka presented this as a means of reducing retain moisture. the necessity of collecting wild mosses and creating It is surprising how difficult it is today to find literature undesirable forest conditions due to drying soils and on the use of bryophytes in plant cultivation, despite the erosion. This consideration should serve as a warning for widespread sale of peat mosses for gardening, potting, air all who desire to use bryophytes for any commercial layering, and other uses. Rather, the use of mosses, purpose, and even on a small personal scale, collection can especially peat moss, seems to be assumed and publications produce local damage. concentrate on finding substitutions for it (e.g. Tripepi et "People have probably used organic materials as an aid al. 1996) or creating the right mix of moss and amendments for plant culture since the eve of human history, but (e.g. Chong & Lumis 2000; Shujun et al. 2004). documentation is scarce" (Raviv et al. 1986). Use of Horticulture is the largest market for moss products in organic materials, including mosses, may not have started Asia (Tan 2003), and probably in most North American that early, but if monkeys can discover the advantage of countries (Muir et al. 2006). In horticulture, mosses find a mosses for getting water to drink, why not? At the niche unparalleled in any other living bryophyte industry beginning of the 18th Century, we find reference to using (Nelson & Carpenter 1965; Tan 2003). In some parts of Chapter 7-1: Gardening: Horticultural Uses 7-1-3 the world, they are routinely mined (Clarke 2008). holding nutrients, especially from dust and rainfall, then Bryophytes, especially peat mosses (Figure 1), have played releasing them slowly over a much longer period than a major role in horticulture for centuries (Perin 1962; normal nutrient residency near the soil surface (Stewart Arzeni 1963; Adderley 1964, 1965). Although their use as 1977; Rieley et al. 1979; Scafone unpubl. data). part of the landscape in gardens has traditionally been mostly an Asian practice, they have commonly been used as soil additives and bedding for greenhouse crops, potted ornamental plants, and seedling beds (Cox & Westing 1963; Sjors 1980). They are stuffed into wire frames to make totem poles to support climbing plants (at the Mossers Lee Plant), topiary (Figure 2), moss-filled wreaths, or baskets (Thomason 1994), or for covering the soil in floral arrangements. One company advertises a birch bark pedestal topped by a moss globe.
Figure 3. Aulacomnium palustre. Species of Dicranum used by the Shuswap Indians of North America to condition the soil for plant growth. Photo by Michael Lüth, with permission.
Figure 2. A swan topiary exhibited in a pedestrian area of Minneapolis, Minnesota, USA. Photo courtesy of David Long.
Overuse of mosses is concerning in several countries. Thus, some horticulturists seek substitutes. The use of rice hulls may provide a more renewable alternative to Sphagnum (Figure 1) peat for horticulture usage (Sambo et al. 2008). Peat has more total pore space and a lower air- Figure 4. Dicranum scoparium. Species of Dicranum used by the Shuswap Indians of North America to condition the soil for filled pore space compared to rice hulls, coinciding with a plant growth. Photo by Janice Glime. higher water-holding capacity and the highest water content at container capacity. Nevertheless, peat had a lower Their ability to sequester nutrients varies with species available water content than the rice hulls, while releasing and type of nutrient. For most taxa, they do not compete its water more slowly. for soil nutrients like phosphorus, but can accumulate from Shipping and Protecting rainfall the potassium, magnesium, and calcium (Timmer 1970). When the mosses later dehydrate, their membranes Sphagnum (Figure 1) is almost indispensable for are damaged, making them leaky. When they rehydrate, shipping live plants, keeping them moist, yet free from nutrients can be dissolved and washed into the soil. It takes mold. In countries where peat is abundant, the damp peat a few hours to a day to repair the damaged membranes, is burned to produce a smoke screen against frost, hence giving the roots beneath a chance to retrieve the nutrients protecting the plants (Thieret 1954). This is one of its uses that are slowly being washed down from the dusty, leaky in Asian countries as well (Tan 2003). mosses. This is dependent also on the force of the rain, Soil Conditioning with light rains more likely to remain on the mosses long enough for them to absorb the nutrients. This seems to be The Shuswap Indians of North America use especially important for potassium, the most soluble and Aulacomnium (Figure 3) and Dicranum (Figure 4) mixed most easily leached nutrient. (See Nutrient chapter in with dirt to make plants healthier (Palmer 1975). As a soil Volume 1 for details.) conditioner, coarse-textured mosses increase water storage Peat, in particular, offers a number of properties capacity; fine-textured mosses provide air spaces (Ishikawa important to the growth of plants. To be suitable for most 1974; Bernier 1992; Bernier et al. 1995). Although root growth, the peat needs to have about equal proportions supporting experiments seem to be lacking, we assume that of air and water retention. The Peat Research Institute mosses improve the nutrient condition of outdoor soils by determined that the inclusion of shrubs and cotton grass 7-1-4 Chapter 7-1: Gardening: Horticultural Uses from the field site could make the peat inconsistent and In England, the Wye College, University of London, alter the water-holding capacity and aeration needed for and Southern Water have cooperated to develop a compost good plant growth. Therefore, they recommended that the that takes advantage of sewage, mixed with peat mosses, proportion of subshrub residues not exceed 3% wet weight, providing a valuable soil conditioner and slow-release that the proportion of cotton grass and sedge residues not fertilizer that can be used for container-grown plants exceed 6%, and that the proportion of Sphagnum (Figure (Lopez-Real et al. 1989). 1) residues be at least 90% (Puustjarvi 1982). One use for the nasty-smelling fish offal takes In remote places, including national parks, remote advantage of the absorptive properties of Sphagnum villages, and other places where sewage systems are not in (Figure 1) to create a superior compost (Martin & place, peat may be mixed with human waste to form Chintalapati 1990), a real boon for getting rid of fish waste. compost (Wikipedia 2017). The extra aeration provided by And, when mixed with fish processing wastes, peat mosses the spaces among the peat plants helps the process of are superior to sawdust and wood shavings in conserving breaking down the sewage. Nevertheless, human nitrogen, but are a bit more expensive (Liao et al. 1995). pathogens can be a problem, with the greatest of these Martin (1992) considered that it should be an easy and being Ascaris eggs (a nematode parasite; Figure 5-Figure inexpensive process to use fish by-products (fish offal) 6) (Hill 2013). A long time or high temperatures are with Sphagnum (Figure 1) peat as a substrate to grow needed to destroy these pathogens. Berger (2011) claims microorganisms for submerged fermentation. Martin that the compost should be free of live pathogens after at conducted experiments on growing fungi and yeast as least two weeks at 55ºC or one week at 60ºC. potential sources of microbial biomass protein for feeding animals. These products, which the fish were willing to include in their diet, served successfully as proteinaceous food for feeding farmed fish. One of the microorganisms tested was the acid-tolerant fungus Scytalidium acidophilum (Figure 7) (Martin & Chintalapati 1989). Martin and Chintalapati found that the culture did not produce any better concentration of the fungus dry weight than when they used a diluted Sphagnum (Figure 1) peat hydrolysate as the substrate source. Martin and Chintalapati (1990) considered that the higher production of nutrients such as nitrogen in the fish offal mixed with peat made this a "promising" source of protein produced by Scytalidium acidophilum.
Figure 5. Ascaris larva hatched on microscope slide, a genus of parasitic worms of concern in human feces. Photo by SuSanA Secretariat, through Creative Commons.
Figure 7. Scytalidium sp. Scytalidium acidophilum is a promising source of protein when grown in fish offal with peat. Photo by Gerardo Garcia-Aguirre, Virginia Vanzinni-Zago, Hugo Quiroz-Mercado, through Creative Commons.
Johnson et al. (1992) similarly worked with people from the Wisconsin Sea Grant Inst to find a suitable use for fish by-products to provide a useful compost. They found that the wide range of values for the C:N ratios and other properties related mostly to the initial C:N ratio and the Figure 6. Ascaris lumbricoides fertilized egg. Presence of time the mix of peat and fish by-products had been allowed these in human feces is of concern when the feces are mixed with to cure. The Sphagnum (Figure 1) peat fish by-product peat as a plant growth medium. Photo by Graham Colm, through composts, especially those with higher C:N ratios, Creative Commons compared well with commercial fertilized mixes. Chapter 7-1: Gardening: Horticultural Uses 7-1-5
As with human waste, destruction of pathogens is important for the fish waste, but Liao and coworkers (Liao 1997; Liao et al. 1997) found that the rise in temperature during composting, plus the ammonia and volatile fatty acids produced, were sufficient to destroy the pathogens. Addition of fir (Abies) or alder (Alnus) chips (Figure 8) caused the compost to stabilize sooner.
Figure 10. SEM image of Synechocystis (Cyanobacteria) on substrate. Photo from BASF, through Creative Commons.
Mosses such as Sphagnum (Figure 1) retain moisture and prevent weed growth, while at the same time discouraging damping-off fungi (Miller & Miller 1979). Culturing
Some mosses, for example the epiphytic Figure 8. Wood chips like those used to stabilize the fish offal/Sphagnum compost and destroy pathogens. Photo through Octoblepharum albidum (Figure 11), are especially Creative Commons. suitable for growing hard-to-grow epiphytic ferns (Arzeni 1963). In the Philippines, Leucophanes octoblepharioides The addition of Sphagnum fuscum (Figure 9) peat to (see Figure 12) and other members of the family are used hog manure reduced the volatile loss of ammonia, a by gardeners and plant growers instead of peat moss in primary source of nitrogen, by 75%, mainly due to lowered potting new plants (Ben C. Tan, pers. comm.). pH, making it a more suitable fertilizer (Al-Kanani et al. Leucobryum (Figure 13) is a suitable medium for inducing 1992a). It offers the added advantage of preventing release good root sprouts on orchid cuttings, sold at U.S. $0.50 per of offensive odors caused by 1,2-ethanediamine, methyl kilo (in 1963), increased to US $1 in 1986 (Tan 2003). The hydrazine, N-methyl methanamine, 3-methyl 2- most popular moss medium for growing orchids, most of butanamine, ethanethioic acid, and methanethiol (Al- which are likewise epiphytes, is Sphagnum (Figure 1), but Kanani et al. 1992b). mosses like Homalothecium arenarium (Figure 14), Hypnum imponens (Figure 15-Figure 16), Leucobryum spp. (Figure 13), Rhytidiopsis robusta (Figure 17), and Thuidium delicatulum (Figure 18) are also useful (Perin 1962; Adderley 1964, 1965). Chen and Chang (2000a, b) had almost 100% survival success when growing the orchid Oncidium (Figure 19) from callus explants on Sphagnum peat. Whereas most of their culture media produced abnormal shoots, both embryo-and shoot-bud-derived regenerants developed into healthy plantlets when potted in Sphagnum and acclimatized in the greenhouse.
Figure 9. Sphagnum fuscum combined with hog manure makes a suitable fertilizer high in nitrogen. Photo by Michael Lüth, with permission.
Rao and Burns (1990) found yet another way of providing nitrogen in the culture of oil-seed rape. They provide Cyanobacteria (nitrogen fixers; Figure 10) and bryophytes in the growing medium. Bryophytes are well known for their ability to harbor Cyanobacteria. Miller (1981) found that bryophytes can even increase the buffering capacity of the soil, surprisingly even against the abrupt changes resulting from fertilizer. And as a Figure 11. Octoblepharum albidum, a moss suitable for mulch, the slow decomposition of peat mosses makes them growing hard-to-grow epiphytic ferns. Photo by Niels Klazenga, much more long-lasting than leaf litter and compost. with permission. 7-1-6 Chapter 7-1: Gardening: Horticultural Uses
Figure 12. Leucophanes sp. Leucophanes octoblepharioides is used instead of peat moss in the Philippines Figure 15. Hypnum imponens growing in a sheet on a log. for planting new plants. Photo by Niels Klazenga, with Photo by Janice Glime. permission.
Figure 13. This epiphytic species of Leucobryum Figure 16. Hypnum imponens, a moss that may be used as a demonstrates its suitability for supporting root growth by hosting substitute for peat in potting young plants. Photo by Janice an epiphytic fern. Photo by Janice Glime. Glime.
Figure 14. Homalothecium aureum may be used as a Figure 17. Rhytidiopsis robusta, a moss that may be used as substitute for peat in potting young plants. Photo by Jan-Peter a substitute for peat in potting young plants. Photo by Blanka Frahm, with permission. Shaw, with permission. Chapter 7-1: Gardening: Horticultural Uses 7-1-7
Figure 20. Mycorrhizal root tips of an Amanita mushroom, partnering with a tree. Photo by Ellen Larsson, R. Henrik Nilsson, Erik Kristiansson, Martin Ryberg, and Karl-Henrik Larsson, through Creative Commons. Figure 18. Thuidium delicatulum, a moss that may be used as a substitute for peat in potting young plants. Photo by Janice Glime.
Figure 19. New Oncidium hybrid pseudobulb that must Figure 21. Cryptothallus (white; in Aneuraceae) and Pinus form a mycorrhizal connection. Photo by Consuelo Tugnoli, pinaster-Tulasnella ectomycorrhizae. Photo courtesy of Martin through Creative Commons. Bidartondo. But one consideration is that orchids are mycorrhizal (see Figure 20). That means they require an appropriate fungal partner in order to successfully form plants from seeds or cuttings. Kreier (2003) reasoned that a fungus that was mycorrhizal to bryophytes might be a good place to find a proper associate for the orchids. Several members of the liverwort family Aneuraceae (Figure 21) are mycorrhizal in association with the fungal genus Tulasnella (Figure 21-Figure 22). Kreier reasoned that if the orchids have the same mycorrhizal fungi, then it should be possible to use those liverwort associations to inoculate the orchids with mycorrhizae from the liverworts. Oberwinkler et al. (2017) reported Tulasnella species are worldwide and likewise are associated with orchids on a Figure 22. Cryptothallus rhizoids colonized by Tulasnella global scale. The possibilities look good. hyphae in a microcosm. Photo courtesy of Martin Bidartondo. 7-1-8 Chapter 7-1: Gardening: Horticultural Uses
Air Layering Horticulturists may have learned some lessons from nature. Mosses in nature provide suitable media for air layering of plants like the heath shrub Calluna (Figure 23) (Scandrett & Gimingham 1991; MacDonald et al. 1995) and even some tropical trees. MacDonald and coworkers (1995) demonstrated that layering was actually associated with the absence or low abundance of the mosses Hypnum cupressiforme (Figure 24) and H. jutlandicum (Figure 25) and Cladonia lichens (e.g. Figure 26). On the other hand, there seems to be a weak connection with layering in Sphagnum spp. (Figure 1 ), Leucobryum glaucum (Figure 27), and pleurocarpous mosses other than Hypnum.
Figure 25. Hypnum jutlandicum, a moss that is negatively associated with air layering of Calluna in nature. Photo by Janice Glime.
Figure 23. Calluna vulgaris, a species that undergoes air layering in mosses in nature. Photo by Willow, through Creative Commons.
Figure 26. Cladonia fimbriata, a moss that is negatively associated with air layering of Calluna in nature. Photo by Paul Cannon, through Creative Commons.
Figure 24. Hypnum cupressiforme, a moss that is negatively associated with air layering of Calluna in nature. Photo by Figure 27. Leucobryum glaucum, a moss that can contribute Michael Lüth, with permission. to air layering of Calluna. Photo by Janice Glime. Chapter 7-1: Gardening: Horticultural Uses 7-1-9
Despite these somewhat weak connections for Calluna (Figure 23), mosses, especially Sphagnum (Figure 1), are used almost exclusively for air layering as a means of propagation of plants. The moss is wrapped (Figure 28) around the area where roots (Figure 29) are to be encouraged, often held in place with cloth mesh, wire, or dark plastic (Figure 30). The moss provides a continuous supply of moisture and encourages the development of adventitious roots while discouraging fungi. Once the roots have formed, the stem can be cut below that point and the explant grown into a new individual (Figure 31). Pant (1989) reports similar use for grafting fruit trees.
Figure 30. Bonsai showing air layering with Sphagnum. Photo from Bonsai Eejit, through Creative Commons.
Figure 28. Wrapping the tree with Sphagnum for air layering to make a bonsai. Photo from Bonsai Eejit, through Creative Commons.
Figure 29. Removal of part of the air layer, exposing roots and new branches of a bonsai. Photo from Bonsai Eejit, through Figure 31. Air layer of oak using moss to make bonsai. Creative Commons. Photo from Bonsai Eejit, through Creative Commons. 7-1-10 Chapter 7-1: Gardening: Horticultural Uses
In addition to its ability to promote root sprouts in orchid cuttings, Sphagnum (Figure 1) is suitable for air layering of a number of kinds of plants, including trees for bonsai (Tan 2003). The moisture and antimicrobial properties are beneficial in the development of new shoots and roots. It appears that preparing a tree for bonsai often involves air layering with mosses (Morrow 2001; Hasegawa 2002; Relf 2009). In their book on bonsai, Yoshimura and Halford (1957) provide instructions for making a bonsai. Mosses, usually Sphagnum (Figure 1), are wrapped around the stem, including a location with young buds, and covered with a material like plastic to retain the moisture. If the plastic is transparent, you can see when the new roots and branches have formed. The lower part of the old stem is then cut off and the layering Figure 33. Potted Fuchsias, a genus whose growth is removed. The bonsai is ready for planting. encouraged by potting with mosses in the mix. Photo by pxhere, through Creative Commons.
Pot Culture Mosses can also encourage growth of potted plants. Pant (1989) reports that Begonia (Figure 32 ) and Fuchsia (Figure 33) bud and flower more profusely in pots where mosses are used to separate the humus-rich top soil from the bottom soil. Members of the Ericaceae, in particular, benefit from the acid of peat mosses. But in Japan, Hypnum plumaeforme (Figure 34), Leucobryum bowringii (Figure 35), L. neilgherrense, and occasionally L. scabrum (Figure 36) fragments are used, mixed with sand or soil, to cultivate Rhododendron (Figure 37) shrubs (Ando 1957). Could it be that these mosses also acidify the Figure 34. Hypnum plumaeforme, a species used in Japan soil? with sand or soil to cultivate Rhododendron shrubs. Photo by Janice Glime.
Figure 32. Potted begonias, a genus whose growth is Figure 35. Leucobryum bowringii, a species used in Japan encouraged by potting with mosses in the mix. Photo by Pixabay, with sand or soil to cultivate Rhododendron shrubs. Photo through Creative Commons. through Creative Commons. Chapter 7-1: Gardening: Horticultural Uses 7-1-11
Figure 36. Leucobryum scabrum, a species used in Japan Figure 38. 3-Inch Jiffy pot of peat moss fibers from Second with sand or soil to cultivate Rhododendron shrubs. Photo Sun Garden Supply. Photo from Second Sun Garden Supply, Taiwan Encyclopedia of Life, through Creative Commons. modified by Janice Glime.
Potting Medium In parts of Asia, horticultural mosses include Vesicularia (Figure 39), Bazzania (Figure 40), Heteroscyphus (Figure 41 ), and Pallavicinia (Figure 42) (Tan 2003). Orchid growers in particular use Leucobryum (Figure 35-Figure 36, Figure 43) and Sphagnum (Figure 1, Figure 44), especially for their ability to store large amounts of water in their hyaline cells (Figure 43-Figure 44).
Figure 37. Rhododendron, a genus that benefits from having mosses in the potting mix. Photo by Pete Bobb, through Creative Commons.
The forestry industry likewise finds peat invaluable for culturing young seedlings (see also Reforestation below). Heiskanen and Rikala (2000) found Sphagnum (Figure 1) peat to be superior to fine sand or peat with perlite, the latter resulting in more weakened seedlings as a consequence of the lower water retention of the medium. However, peat is not always readily available. Israeli researchers found that composted cattle manure mixed with grape marc were good substitutes for peat in that country where peat must be imported; the substitutes were likewise effective at suppressing plant pathogens (Chen et al. 1992). In other cases, the pots themselves (Figure 38) are made of mosses. These are good for starting seedlings and Figure 39. Vesicularia vesicularis var. vesicularis. The can be planted without removing the plants. Roots will genus Vesicularia is among the horticultural mosses in Japan. eventually penetrate the pot and grow into the soil. Photo by Michael Lüth, with permission. 7-1-12 Chapter 7-1: Gardening: Horticultural Uses
Figure 43. Leucobryum glaucum leaf cells showing alternating hyaline and photosynthetic cells. Photo by Ralf Wagner
Figure 44. Sphagnum palustre photosynthetic (green) and hyaline cells. Note that the hyaline cells are not short cells, but Figure 41. Heteroscyphus fissistipus, a leafy liverwort. The are elongate cells with bars across them. Photo by Malcolm genus Heteroscyphus is among the horticultural bryophytes used Storey through Creative Commons. in Japan. Photo by David Francis, through Creative Commons. Sphagnum (Figure 1) and Leucobryum (Figure 35- Figure 36) seem to be particularly preferred as a potting medium for orchids (Tan 2003). Tan reported the use of Leucobryum as a substitute for peat moss to grow orchid cuttings in Asia. The mosses, especially Sphagnum, were good as a potting medium for a variety of seeds. But in North America, diversity of mosses as a potting medium seems to be absent. I searched with Google for "potting medium moss" and stopped after the 20th hit. All 20 of the mosses were named as peat moss or Sphagnum (Figure 1).
Dangers of Peat Culturing There are drawbacks to using mosses in culturing of some plants. We have seen that Sphagnum (Figure 1) can be dangerous because of its cohabiting fungus that causes sporotrichosis (Chapter 1 of this volume). In containers of conifer seedlings, they can choke young seedlings, compete Figure 42. Pallavicinia lyellii, a thallose liverwort. The for nutrients, and repel water (Haglund et al. 1981). But genus Pallavicinia is among the horticultural bryophytes used in they can also pose serious dangers. But causing fires? As Japan. Photo by Des Callaghan, with permission. Michael Richardson shared with Bryonet on 20 June 2013, Chapter 7-1: Gardening: Horticultural Uses 7-1-13 peat, including shrubs and other debris along with the Culturing Mushrooms and Other Fungi mosses, is good potting material, but it can be flammable under the wrong circumstances. The oxygen available in Sphagnum (Figure 1) peat is the substrate of choice as the pot can permit decay to occur, causing heat that is casing medium for cultivating the common grocery store amplified if the pot is in the sun. An article in the mushroom, Agaricus bisporus (Figure 47) (Eicker & van Northumberland News reported a house fire in June 2013 Greuning 1989; Reddy & Patrick 1990; Jarial et al. 2005). that was attributed to a pot with peat mosses on a second (Casing is the process in which a non-nutritious layer, in floor balcony. The deputy chief of the fire department said this case peat, is applied over the colonized substrate so that the dry peat can easily ignite and can, after being in that the mycelium has access to more moisture, thereby direct sunlight long enough, ignite by itself. This was not increasing the size and number of growths.) Sungrow had his first experience with flower beds on fire. His advice is a multi-million-dollar contract from Campbell (of to use non-combustible flower pots (not plastic), such as Campbell soup fame) to improve mushroom culturing concrete or metal. using a Sphagnum mix (Vitt, pers. comm.; Miller 1981). However, in places such as South Africa, where there is no Covering Pot Soil peat, substitutes are necessary. The need for peat substitutes led Eicker and van Greuning (1989) to test other Sheet mosses are frequently used to cover the soil in substrata and compare, but peat still gave the highest yields pots housing flowering plants (Nelson & Carpenter 1965). compared to eight other materials, with only weathered, This is especially true when they are sold by florists. spent compost offering similar results. Other types of Species of Leucobryum (not a sheet moss; Figure 35- mushrooms are grown in peat as well, such as Pleurotus Figure 36) can be used for this purpose, providing a pale ostreatus (Figure 48) (Manu-Tawiah & Martin 1986). green color contrast to the green of most tracheophyte leaves. In some cases, the strong anti-microbial properties of bryophytes might reduce invasions of bacteria and fungi. Mat-forming mosses are typically sold as sheet mosses (Figure 45) (Peck et al. 2001). These are pleurocarpous mosses that grow horizontally, often on logs. Collectors strip the logs, and sometimes low branches, of their mats. In the eastern USA, one of the mosses used is Thuidium (Figure 46).
Figure 47. Agaricus bisporus, a species commonly grown in Sphagnum. Photo by I. G. Safonov, through Creative Commons. Figure 45. A package of sheet moss being sold in a gardening shop in Ohio, USA. Photo by Janice Glime.
Figure 46. Thuidium sheet moss, sold at a gardening shop in Figure 48. Pleurotus ostreatus on a mossy tree trunk. This Ohio, USA. Photo by Janice Glime. species can be cultivated in peat. Photo from Charl de Mille-Isles. 7-1-14 Chapter 7-1: Gardening: Horticultural Uses
In an attempt to make further improvements in mushroom success, Beyer (1997) sought ways to reduce the effect of accumulated substances on late mushroom crops. Surprisingly, he found that the addition of Hypnum (Figure 15-Figure 16, Figure 24-Figure 25) peat to the compost improved later break yield, but the addition of Sphagnum (Figure 1) did not. One of the concerns is that the peat becomes infested with nematodes (Figure 49) and may carry Pseudomonas tolaasii (see Figure 50), the cause of bacterial blotch, both of which cause serious diseases to the mushrooms (Nikandrow et al. 1982).
Figure 51. Agaricus campestris, a species that grows well in a peat fermentation medium. Photo by Andreas Kunze, through Creative Commons.
Figure 49. Soil nematode, a common pest in Sphagnum that may carry the bacterium Pseudomonas tolaasii. Photo by Christina Menta, through Creative Commons.
Figure 52. Morchella esculenta, the common morel, can be cultured in a bed of peat. Photo by Janice Glime.
A mixture of Sphagnum (Figure 1) with fish offal promises to be a suitable substrate for culturing the acid- tolerant fungus Scytalidium acidophilum (see Figure 7), which is considered to be a promising source of microbial protein (Martin & Chintalapati 1990). However, not all fungal cultures seem to benefit from peat mixtures. In one commercial operation, the yield of mushrooms improved when the peat was omitted from the cultivation medium Figure 50. Pseudomonas, a bacterium carried by soil (Smith 1983). nematodes. Photo by Janice Carr, through public domain. Reforestation Martin and Bailey (1983) succeeded in using peat as a fermentation medium in which acclimated fungi could be The genus Tulasnella (Figure 21-Figure 22) is a grown. They were more successful with the common mycorrhizal partner with several members of the thallose mushroom Agaricus campestris (Figure 51) than with the liverwort family Aneuraceae (Figure 21). If this fungus is morel Morchella esculenta (Figure 52) (Martin 1982). likewise a partner with trees, then it should be possible to Martin and Bailey considered that growth inhibitors might use those liverworts to help the trees to become established be present in peat. Using sulfuric acid hydrolysates with (Kreier 2003). In fact, Cryptothallus (Figure 21), a autoclaved peat released a liquid that, when supplemented member of the Aneuraceae, shares its fungal partner with with nutrients, would enhance growth and crude protein at least some members of the birch (Betula; Figure 53) and content of these two edible fungi. Nutrient-supplemented pine (Pinus; Figure 54) genera. Kreier found that both peat hydrolysates enhance growth and crude protein liverworts Riccardia palmata (Figure 55 ) and R. latifrons content of fungal biomass. (Figure 56) grew on rotten wood and were well infected by Chapter 7-1: Gardening: Horticultural Uses 7-1-15 mycorrhizal fungi. Kreier also figured it would be relatively easy to disperse these liverworts on the forest floor, and that they would spread easily, preparing the soil with mycorrhizae that could partner with the trees. At that time, the fungi had been grown in culture but not the field. However, the discovery of rhizoidal bridges in tropical Aneura (Aneuraceae; Figure 57) provided a hopeful twist. In 2017, Oberwinkler et al. noted that Tulasnella species are worldwide in distribution and that they may occur in many forest ecosystems in association with wood. And we have already noted that they form mycorrhizal associations with orchids.
Figure 55. Riccardia palmata, a species that grows on rotten wood and is infected by mycorrhizal fungi. Photo by Bernd Haynold, through Creative Commons.
Figure 53. Betula pendula. Some members of the genus Betula share their fungal partner with the thallose liverwort Cryptothallus. Photo by Percita, through Creative Commons.
Figure 56. Riccardia latifrons, a species that grows on rotten wood and is infected by mycorrhizal fungi. Photo by Bernd Haynold, through Creative Commons.
Figure 54. Pinus strobus. Some members of the genus Figure 57. Aneura pinguis, a species that might be Pinus share their fungal partner with the thallose liverwort associated with Tulasnella on wood. Photo by Li Zhang, with Cryptothallus. Photo through Creative Commons. permission. 7-1-16 Chapter 7-1: Gardening: Horticultural Uses
Container Gardens 18) (C. Delgadillo, pers. comm.). In the Pacific Northwest of North America, Leptobryum pyriforme (Figure 72), Mosses are commonly used in container gardens with known as Kyoto moss, is sold for bonsai trays (J. Christy, bonsai (dwarfed ornamental tree; Figure 58 ) and bonkei pers. comm.). I would expect Climacium and Polytrichum (tray landscape; Figure 59), where they help to stabilize the to serve well as trees in miniature landscapes as well. soil and retain moisture for the shallow roots.
Figure 58. Bonsai at Dawes Arboretum, Ohio, USA, Figure 60. Atrichum angustatum, in a genus used to showing dwarfed tree and mosses at base. Photo by Janice Glime. simulate forests in tray gardens. Photo by Keith Bowman, with permission.
Figure 59. Outdoor bonkei in a Japanese private garden. Selaginella, a relative of club mosses and not a true moss, is used to represent a tree, with mosses growing on the rocks that form the basin for a small "lake." Photo by Janice Glime.
Designers select the species of mosses to serve particular functions in the container landscapes. Large, upright mosses such as Atrichum (Figure 60 ), Climacium (Figure 61 ), Dicranum (Figure 4) , Polytrichum (Figure 62 ), and Rhodobryum (Figure 63) simulate forests. Bryum argenteum (Figure 64) has a silvery, compact look that can simulate grasslands, and Leucobryum (Figure 27) usually has the role of a mountain. For snow-capped mountains, Racomitrium canescens (Figure 65) provides a frosted look. Physcomitrium (Figure 66-Figure 67), often a volunteer in greenhouse flower pots, is so miniature as to appear like a moss, or maybe a grass, in a landscape of Leucobryum mountains. Barbula unguiculata (Figure 68 ), Funaria hygrometrica (Figure 69), and Weissia controversa (Figure 70) can contribute to needs of intermediate size. In Mexico, some mosses are even used for fake bonsai: Campylopus (Figure 71), Dendropogonella rufescens, Hypnum (Figure 15-Figure Figure 61. Climacium dendroides, simulating trees in a dish 16, Figure 24-Figure 25, Figure 34), and Thuidium (Figure garden. Photo by Keith Bowman, with permission. Chapter 7-1: Gardening: Horticultural Uses 7-1-17
Figure 65. Racomitrium canescens, a moss that is used to Figure 62. Polytrichum juniperinum, in a genus used to simulate snow on mountains. Photo by Michael Lüth, with simulate forests in tray gardens. Photo by Janice Glime. permission.
Figure 63. Rhodobryum roseum, in a genus used to simulate Figure 66. Physcomitrium pyriforme in a dish garden. forests in tray gardens. Photo by Michael Lüth, with permission. Photo by Michael Lüth, with permission.
Figure 64. Bryum argenteum, a species used to simulate grasslands or mountains in tray gardens. Photo by Tushar Figure 67. Physcomitrium pyriforme with capsules, a Wankhede, with permission. common volunteer in flower pots. Photo by Janice Glime. 7-1-18 Chapter 7-1: Gardening: Horticultural Uses
Figure 72. Leptobryum pyriforme, a species that is used in Figure 68. Barbula unguiculata, a moss of intermediate size the Pacific Northwest, USA, in bonsai trays. Photo by Michael to fill in as grass or other intermediate needs. Photo by Michael Lüth, with permission. Lüth, with permission. Bonkei Miniature tray landscapes [bonkei or saikei (art of creating tray landscapes that combine miniature living trees with soil, rocks, water, and related vegetation); Figure 73- Figure 76] in Japan use mosses to provide appropriate texture and color with little danger of damage due to drying (Kawamoto 1980; Oishi 1981). Such trays can delight the bed-ridden. Gerritson (1928) arranged sixteen species of mosses in various stages of maturity to provide a changing landscape for a hospitalized friend: "Each day the mosses had changed appearance; so each day added a new joy. The nurses came from time to time to see and admire. Figure 69. Funaria hygrometrica, a moss of intermediate Other patients shared its freshness and beauty. Visitors, too size to fill in as grass or other intermediate needs. Photo by were invited to see the charm of a 'platter of mosses.'" Michael Lüth, with permission.
Figure 73. Bonkei with its miniature landscape containing Figure 70. Weissia controversa, a moss of intermediate size mosses to simulate mountains. Photo courtesy of Hironori to fill in as grass or other intermediate needs. Photo by Michael Deguchi. Lüth, with permission.
Figure 71. Campylopus introflexus; the genus Campylopus is used in Mexico for fake bonsai. Photo by Michael Lüth, with Figure 74. Bonkei with mosses simulating trees with a rocky permission. crag. Photo courtesy of Hironori Deguchi. Chapter 7-1: Gardening: Horticultural Uses 7-1-19
Dish Gardens Dish gardens (Figure 78) are a scaled down version of bonkei. The size may not be scaled down, but they typically do not represent a landscape and may have only one bryophyte species (Figure 78), sometimes as ground cover for flowering plants like spring bulbs (Figure 79).
Figure 75. Bonkei simulating a volcano and surrounding mountains and forests. Photo courtesy of Hironori Deguchi.
Figure 76. Selaginella (a club moss relative) and moss Figure 78. Dish garden of moss. Photo courtesy of J. Paul bonsai, Kyushu, Japan. Photo by Janice Glime. Moore.
For making these miniature landscapes, Schenk (1997) recommends the usual potting mix of humus, including peat moss, ground-up tree bark, or rotted sawdust. He cautions that sand, vermiculite, or perlite can be used, but that they must be kept moist because they tend to have larger spaces and dry quickly near the surface, leaving the moss with no source of moisture. Even in this seemingly harmless occupation, one must use caution against allergens. Tray gardens and other forms of bonsai and dish gardens may use Sphagnum (Figure 1) peat as a medium or even as the plants of interest (Figure 77). This moss is well known for its ability to harbor the fungus that causes sporotrichosis (Dong et al. 1995).
Figure 77. Sphagnum moss pot in Japan, a potential source Figure 79. Dish garden for spring bulbs in cafe in of allergens. Photo courtesy of Hironori Deguchi. Helsingborg, Sweden. Photo courtesy of Irene Bisang. 7-1-20 Chapter 7-1: Gardening: Horticultural Uses
Figure 82. Children creating their first dish garden, under the tutelage of Annie Martin, MountainMoss. Photo courtesy of Annie Martin.
Figure 80. A cross between a bonsai arrangement and a dish garden. Photo courtesy of Lars Hedenas and Irene Bisang.
Annie Martin, a prize-winning gardener and landscaper (Figure 81), runs classes for both adults and children in which she teaches them how to make dish gardens and terraria (Figure 82-Figure 83).
Figure 83. The proud owner of a new dish garden that she created. Photo courtesy of Annie Martin.
Figure 81. The award-winning creator (Annie Martin) of Similar to the dish gardens, moss rocks (Figure 84- dish gardens, terrariums, and moss gardens is shown here framed Figure 85) have become popular in some places. These by her own artistic bryophyte creation. Photo courtesy of Annie typically have a species of moss growing in a depression or Martin. on the surface of a rock. Chapter 7-1: Gardening: Horticultural Uses 7-1-21
Figure 84. Dicranodontium denudatum stone pots in shop in Hakone, Japan. These are a variation on the dish garden, but the mosses are grown on the surface or in a depression of a natural rock and typically have only one moss species. Photo courtesy of Figure 87. This bonsai arrangement incorporates features of Hironori Deguchi. bonkei with rocks and mosses giving it the look of a miniature forest. Photo by Janice Glime.
Figure 85. Moss-Rocks-logo at Moss and Stone Gardens, Pennsylvania, USA, showing a more formal American version. Photo with permission from David Smith.
Bonsai Figure 88. Bonsai at Dawes Arboretum, Ohio, USA. This The term bonsai (Figure 86) refers to a dwarfed bonsai uses a deciduous tree, and bryophytes can warn its owner ornamental tree or shrub grown in a pot and prevented from to water it before the leaves begin to drop or become crispy. reaching its normal size. Inoue (1972) pointed out that Photo by Janice Glime. moss bonsai and moss bonkei (tray landscapes) are popular in Japan by both amateurs and professional horticulturists. But even bonsai trees are potted in wide pots and the soil is typically covered with mosses (Figure 86-Figure 89).
Figure 86. Bonsai at Dawes Arboretum, Ohio, USA, showing the dwarfed tree and mosses at its base. Photo by Janice Figure 89. Bonsai using the fern Osmunda lancea. Glime. Courtesy of Hironori Deguchi. 7-1-22 Chapter 7-1: Gardening: Horticultural Uses
The mosses can contribute to the success of the bonsai. When the mosses appear dry, you can be sure your bonsai needs water (Figure 90-Figure 91). However, mosses are not always the friends of the bonsai. The continuous moisture of the mosses can inhibit root growth and promote sudden fungal attacks. The experts advise removing the mosses each autumn to reduce fungal damage (Bland 1971).
Figure 92. Bonsai at Dawes Arboretum, Ohio, USA, illustrating mosses covering the pot and signalling when the tree roots need more water. Photo by Janice Glime.
In Malaysia, bonsai makers typically use the acrocarpous mosses Bryum (Figure 93) and Philonotis Figure 90. Bonsai in Dawes Arboretum, Ohio, USA. (Figure 94), and sometimes the pleurocarpous mosses Mosses on the roots are a good indicator when the soil is Isopterygium/Pseudotaxiphyllum (Figure 95) and becoming dry and the tree needs water. Photo by Janice Glime. Vesicularia (Figure 39) and the thallose liverwort Riccia (Figure 96) (Tan 2003). In Singapore, the moss Ochrobryum kurzianum is imported from Thailand for ornamental use in bonsai arrangements. In Japan, Leucobryum (Figure 27) is common in bonsai landscape design.
Figure 91. Bonsai on wood, increasing the need for bryophytes to maintain root moisture and warn when it is time to water it. Photo courtesy of Annie Martin, MountainMoss.
In India, bonsai is included in horticultural texts. Dhanda (1984) suggests that the bonsai may be finished off with a layer of moss on top (Figure 92). Yoshimura and Halford (1957) likewise consider the mosses growing around the bonsai to be important. The mosses provide several advantages. They add aesthetic appeal, creating a more natural looking landscape. And they make watering easier, permitting a raised base on the tree while catching Figure 93. Bryum capillare with capsules, in a genus used in the water and protecting the furniture. bonsai in Malaysia. Photo by Michael Lüth with permission. Chapter 7-1: Gardening: Horticultural Uses 7-1-23
In Asia, species of Sphagnum (Figure 1) are used to line hanging baskets (Tan 2003). Its ability to hold water and its antimicrobial activity make this a good substrate for the roots of flowering plants. A wire frame is used to give the basket support, with mosses wound among the wires or laid within to provide the structure. Not only do they make an attractive, natural- looking basket, but they reduce the need for frequent watering (Lohr & Pearson-Mims 2001). Species of Hypnum (Figure 15-Figure 16, Figure 24-Figure 25, Figure 34) and Sphagnum (Figure 1) are commonly used for this purpose. The long, stiff stems of Polytrichum (Figure 62) permitted the early Romans to weave it into baskets (Bland 1971), but these most likely did not have a horticultural purpose.
Figure 94. Philonotis fontana, in a genus used in bonsai in Malaysia. Photo by Michael Lüth, with permission. Terraria The terrarium, a drier plant version of the aquarium, is often arranged like an enclosed garden (Figure 97), a miniature garden like the container gardens. Because of its small size, bryophytes are often used to give the look of mountains (Figure 98); dry brooks made of pebbles ramble between clumps of various hues of green. But bryophytes are not easy to grow in such conditions. If the container is fully open (Figure 98, Figure 99), mosses soon dry out and become crispy. If it is sealed (Figure 97, Figure 100-Figure 103), as many terraria are, fungi can easily grow. The best choice is to leave the top partially open to permit air circulation.
Figure 95. Pseudotaxiphyllum elegans, in a genus used in bonsai in Malaysia. Photo by J. C. Schou, with permission.
Figure 96. Riccia sorocarpa, in a genus used in bonsai in Malaysia. Photo by
Hanging Baskets Mosses are often used in the construction of hanging baskets for flowers (Smith 1996). In California, USA, meter-long "strips" 8-10 cm wide are used to make Figure 97. Closed terrarium from MountainMoss, showing hundreds of baskets per week! miniature garden. Photo courtesy of Annie Martin. 7-1-24 Chapter 7-1: Gardening: Horticultural Uses
Figure 98. Open terrarium from MountainMoss. Note the mound of Leucobryum which is sometimes used to simulate mountains. Photo courtesy of Annie Martin.
Figure 101. Tiered terrarium from MountainMoss. Photo courtesy of Annie Martin.
Figure 99. Open terrarium with moss. Photo courtesy of J. Paul Moore, with permission.
Figure 100. In some covered terraria, small holes with plugs, similar to the green ones seen here, can be opened and even kept Figure 102. Terrarium with lid. Note the tiny figure that open to maintain at least some air movement and reduce turns the tall mosses into "trees." Photo by Erin, through Creative condensation. Photo courtesy of Annie Martin of MountainMoss. Commons. Chapter 7-1: Gardening: Horticultural Uses 7-1-25
Figure 104. Wardian Case, similar to the first terrarium by Nathaniel Bagshaw Ward. Image through public domain.
Choice of mosses depends in part on how moist you intend to keep it and in part on the effect you want to achieve. Polytrichum (Figure 62) can survive in a somewhat dry terrarium but will easily be covered with mold when it is too damp. Likewise, Leucobryum (Figure 27) likes it airy with good circulation. Ceratodon purpureus (Figure 105) is sometimes successful, again requiring at least some air circulation. Schenk (1997) states, "I must tell the whole truth by identifying the great enemy of terrarium gardening with native woodlanders, for there is one: mold." He admonishes that most terraria have a short life due to this problem. My own experience certainly agrees.
Figure 103. Tall moss terrarium that not only permits taller plants like ferns, but also provides more air space, reducing fungal takeover. Photo by Ken Gergle, through David Spain.
It seems appropriate to cite the first terrarium, known as the Wardian case (Figure 104), invented by Nathaniel Bagshaw Ward (1791-1868) (Hershey 1996). He had fallen in love with plants on a trip to Jamaica and despite ultimately pursuing a profession as a physician, he pursued plants through his attempts at gardening. But, sadly, his attempts at a moss and fern garden failed, due severe air Figure 105. Ceratodon purpureus, a species used in bonsai pollution in the outskirts of London. It was this failure that in Malaysia. Photo by Michael Lüth, with permission. led him to invent the Wardian case, or terrarium. He had placed a "chrysalis" (actually a moth pupa) in a bottle and Funaria hygrometrica (Figure 69) can be encouraged observed it daily. Then, to his surprise, a "seedling" fern in more moist conditions, but it still needs circulation. and a grass appeared. He considered the conditions and With a little luck it will even produce capsules. We noted the need for "a moist atmosphere free from soot or successfully maintained F. hygrometrica in an uncovered other extraneous particles; light; heat; moisture; periods of aquarium in our university greenhouse. These lasted for rest; and change of air." He moved the bottle to the outside several years, but we avoided getting tap water on them and of a northern window and there the plants thrived for four only used misting from distilled water or tap water that had years with no additional attention! been allowed to sit to allow the chlorine to escape. 7-1-26 Chapter 7-1: Gardening: Horticultural Uses
Schenk (1997) suggests that a container the size of an aquarium (Figure 106) is best, smaller ones being more subject to mold. Air space is of the essence, and it needs to circulate. He considers a potting mix to be suitable, whereas it does not tend to work well in open-air gardens. On the other hand, if the bryophytes have their own deep brown portions (Figure 107), no substrate is necessary. Charcoal may be added to the substrate to absorb excessive acidity and gases produced by decay. Little water is needed as it will recycle (Figure 108) within the nearly sealed container. Adding flowering plants can add color (Figure 109). Mosses that are collected wet generally do not need additional water and may even need to be dried by leaving the terrarium open wide for a day or two. Slightly dry mosses can be moistened with 30-35 ml (2-3 tablespoons) of water; totally dry ones may require up to 70 ml (1/4 cup) (Schenk 1997). Figure 109. Mix of a variety of plants with color (red-leafed Begonias, pale Tillandsias) and rocks in kitchen terrarium built in an aquarium. Photo by Janice Glime.
Maintenance for the first few days after planting is essential to avoid an immediate mold attack. Schenk (1997) advises that if a heavy dew (Figure 108, Figure 110) appears on the walls of the container, open it and dry the walls. This should be repeated daily until morning brings only a light condensation on the upper half of the walls of the container. When you discover, probably in a few weeks, that there is no longer any morning dew, it is time to add water, but not much. Figure 106. Kitchen terrarium in an aquarium. Photo by Janice Glime.
Figure 107. Campylopus flexuosus with brown base, needing no substrate. Photo by Michael Lüth, with permission.
Figure 110. Terrarium with moss, showing severe condensation that must be removed by drying the walls or keeping the container open until it is gone. Photo by J. Paul Moore, with permission.
After all this care, Schenk (1997) warns that the terrarium will most likely last only three weeks! (I have had better success than that with larger aquaria.) That can be extended by providing fluorescent lights to avoid the Figure 108. Condensation on wall of kitchen terrarium, etiolated growth so noticeable in low light. Nevertheless, a endangering a mold outbreak. Photo by Janice Glime. mold garden is most likely to ensue within this short time, Chapter 7-1: Gardening: Horticultural Uses 7-1-27 and great care and luck are needed to find the right wetting Using this method, she has kept one bottle of mosses, and drying cycle. including Sphagnum (Figure 1), for more than three years. Within those first few weeks, a moss garden terrarium And even in a terrarium there is competition. Her Saelania can be full of surprises, with mushrooms appearing, glaucescens (Figure 112) had been growing well for five capsules extending, and the somewhat rapid but unnatural years, but Mnium (Figure 113) began to overtake it. elongation of the moss stems in low light. One of the contributors to the demise of the moss terrarium indoors is the warm temperatures night and day indoors. If there is a cool location for the terrarium, it might survive a longer display, and surely in the refrigerator it would last, but would be of little use, not to mention suffering from lack of light. One last caution I would insert is that lichens are to be avoided if one wishes to maintain a moss terrarium for any length of time. In the moist conditions of confinement, they will soon spread their fungi broadly and overtake the moss, albeit no longer as lichens, but nevertheless encroaching rapidly upon the surfaces of green. If lichens are to be enjoyed in this terrarium, it must by all means be kept open and the mosses provided with water occasionally as needed, perhaps with dry periods, but not too frequently. I was relieved to read this moss gardener's treatment of the terrarium. If such an expert as Schenk was able to Figure 111, Hyophila involuta, in a genus that lasts about one year in a terrarium. Photo by Michael Lüth, with permission. maintain such a terrarium garden for only three weeks, I felt elated that I, too, had succeeded on occasion to maintain one for so long! In short, if you wish to maintain a terrarium of bryophytes for a lengthy period of time, my best advice to you is Good Luck! Echoing the comments above, David Wagner (Bryonet 23 June 2013) suggested that the problem with terraria is that they are usually closed containers. He has observed mosses doing well for several years in an open water table where water flowed across the water table. This depends on water that is low in dissolved minerals and may require a filtering system on tap water. One danger in closed terraria, especially small ones, is that the enclosed humidity and lack of air movement encourages the growth of fungi and soon they take over. Alison Downing (Bryonet 23 June 2013) reported success in growing bryophytes for display by using fish tanks for the mesic species. She attributed the success to using water from a garden pond, citing high levels of chlorine in tap water as a possible source of bryophyte Figure 112. Saelania glaucescens, a moss that has survived collapse. Nevertheless, these bryophytes in the aquaria a terrarium for five years, but that is being overtaken by Mnium. also have a limited life. Photo by Janice Glime. Ben Tan (Bryonet 23 June 2013) found that bryophytes transplanted to a closed terrarium usually survived from 6- 18 months. Even on moss walls, the bryophytes needed complete replacement every two years to maintain aesthetic appeal. This is with no fertilizer, watered with tap water, in a fully air-conditioned room. Even Bryum (Figure 93) and Hyophila (Figure 111) last only about one year in a self- contained environment indoors with proper light and high humidity. Alison Dibble (Bryonet June 2013) reports better success. She grows bryophytes on the windowsill all winter in small bonsai dishes. Others are in clear plastic boxes or a clear glass container with a loose-fitting lid. If the container is open, Dibble soaks the mosses in the sink once a week. In the summer she puts them outside under Figure 113. Mnium marginatum overgrowing other mosses, the overhang of a north-facing boulder and lets nature do a problem it can cause in a terrarium. Photo by Jan-Peter Frahm, the watering, but if there is a dry spell she waters them. with permission. 7-1-28 Chapter 7-1: Gardening: Horticultural Uses
Appropriate moisture levels are clearly a problem. Yoest (2011) suggests that if mosses and flowering plants or other tracheophytes are to co-exist, one must periodically remove the covering to water the tracheophytes. Keep the cover off for a day or two to allow excess water to escape. When you return the lid, check for condensation and vent the container until you achieve the right balance. In a dish garden or terrarium, proper drainage is needed, so putting pebbles on the bottom can help. Contrary to what most people might expect, the humidity level must be kept low. This condition can often be achieved by using a cover with a small opening at the top. As an alternative, David Spain (in Yoest 2011) suggests removing the cover in the daytime and covering it at night. He has created a terrarium with a tall cover over a dish, using this routine. The terrarium has the fern ebony spleenwort (Asplenium platyneuron; Figure 114) and the Figure 115. Climacium americanum with capsules in moss mosses Dicranum scoparium (Figure 4), Leucobryum garden, a species that looks good in a terrarium. Photo by Janice Glime. glaucum (Figure 27), Hypnum imponens (Figure 15- Figure 16), and Campylopus introflexus (Figure 71). (Be I have a large (40-gallon) terrarium with begonias, careful with the latter – it is an invasive species, so don't ferns, Tillandsia, and a few mosses (Figure 106). Like just throw it outside when you no longer want it.) Another Spain and Yoest, when I water it, I leave the cover partially of Spain's favorites is the moss Climacium americanum open for a few days until the excess water evaporates. (Figure 115). Spain concludes that "mosses do not make Then I cover it and it will last about six months before it ideal terrarium plants." needs to be watered again. I have limited success with the mosses because they seem to produce weak stems and to become infected with fungi. Extra aeration helps to avoid fungi, but then more frequent watering is needed, at least for the tracheophytes. Bryophytes as Pests Sadly, bryophytes can even be considered to be pests in gardens and flower pots (e.g. Newby et al. 2007). Greenhouse managers are often dismayed at having the invasion of Marchantia polymorpha (Figure 116) in many of their flower pots. But it is their method of watering that distributes this liverwort everywhere. The heavy force of water from a hose propels the gemmae out of their cups and onto bare soil nearby. These liverworts often arrive in the greenhouse initially as free-loading passengers in flower pots of new flowers or ferns, either as plants or as gemmae. And the greenhouse satisfies their growing needs.
Figure 114. Asplenium platyneuron, a fern that survives in Figure 116. Marchantia polymorpha with gemmae cups. a terrarium that is opened daily and closed at night. Photo by F. Gemmae are splashed about in greenhouses when plants are B. Matos, through Creative Commons. watered. Photo by David T. Holyoak, with permission. Chapter 7-1: Gardening: Horticultural Uses 7-1-29
Another species known throughout most of North America only in greenhouses is the thallose liverwort Lunularia cruciata (Figure 117). Like species of Marchantia (Figure 116), it produces gemma in cups, in this case crescent-shaped cups, and these likewise are easily dispersed by typical greenhouse watering methods.
Figure 119. Orthodontium lineare, a widespread moss species that often travels in flower pots. Photo by Michael Lüth, with permission.
Figure 117. Lunularia cruciata with gemmae cups and gemmae that are distributed with rain or watering in a greenhouse. Photo by Des Callaghan, with permission.
Other volunteers that I have observed include Bryum spp. (Figure 64, Figure 93), Leptobryum pyriforme (Figure 72 ), and Ceratodon purpureus (Figure 105). These are all mosses, with the latter two frequently producing numerous capsules and thus most likely spreading by spores. Bryum argenteum (Figure 64) has detachable terminal buds that will grow new plants. It is likely that it benefits in the same way as the gemmae of the two liverwort species. A final caution is appropriate. Some bryophytes are Figure 120. Pseudoscleropodium purum, a widespread invasive, although much less so than their flowering plant moss species that often travels in flower pots and also is used for packing. Photo by Phil Bendle, with permission. counterparts. Nevertheless, they can disrupt ecosystems, changing the success of seed germination, affecting the invertebrates that live there, and changing the hydrology. In addition to the ones that like to travel among flower pots, the most invasive and widespread of these are Campylopus introflexus (Figure 71), Eurhynchium praelongum (Figure 118), Lunularia cruciata (Figure 117), Orthodontium lineare (Figure 119), Pseudoscleropodium purum (Figure 120), and Lophocolea semiteres (Figure 121) (Essl et al. 2013; Mateo et al. 2015). Some of these have spread due to their use as packing material, especially for shipping plants in the horticultural industry.
Figure 121. Lophocolea semiteres, a widespread leafy liverwort species that often travels in flower pots. Photo by David Long, with permission.
Summary Peat mosses have been widely used in horticulture as soil additives, and for bedding, as well as forming the foundation for topiary, wreaths, and hanging
baskets. Their ability to add moisture makes them ideal Figure 118. Eurhynchium praelongum, a widespread moss as a shipping medium for plants. species that often travels in flower pots. Photo by Janice Glime. 7-1-30 Chapter 7-1: Gardening: Horticultural Uses
Peat mosses are used as soil conditioners, Bland, J. 1971. Forests of Lilliput. Prentice-Hall, Englewood providing a holding medium for nutrients, releasing Cliffs, N. J., 210 pp. them slowly following drying. They provide good Chen, J. T. and Chang, W. C. 2000a. Efficient plant regeneration compost, especially when mixed with such waste through somatic embryogenesis from callus cultures of products as fish offal or sewage. Some peat mosses Oncidium (Orchidaceae). Plant Sci. 160: 87-93. provide additional fixed nitrogen through their Chen, J. T. and Chang, W. C. 2000b. Plant regeneration via Cyanobacteria flora. Their antibiotic properties embryo and shoot bud formation from flower-stalk explants discourage damping-off fungal growth while of Oncidium Sweet Sugar. Plant Cell, Tissue Organ Culture maintaining moisture. These same properties make 62(2): 95-100. them good for air layering. All of these properties Chen, Y., Inbar, Y., and Hadar, Y. 1992. Composted residues make peat mosses good culture media and potting reduce peat and pesticide use. Biocycle 33(6): 48-51. mixes, but other relatively dense mosses work well Chong, C. and Lumis, G. P. 2000. Mixtures of paper mill sludge, also. wood chips, bark, and peat in substrates for pot-in-pot shade Peat mosses have been used in forestry to culture tree production. Can. J. Plant Sci. 80: 669-675. young seedlings and in the food industry to culture Clarke, D. 2008. The origins and development of the peat mushrooms and morels. industry in Ireland. Peatlands Internat. 1/2008: 12-15. Small mosses work well in container gardens such Cox, R. L. and Westing, A. H. 1963. The effect of peat-moss as bonsai and bonkei, where various species are used to extracts on seed germination. Proc. Indiana Acad. Sci. 73: simulate different aspects of miniature landscapes. 113-115. Terraria are more difficult, with mold being a frequent Dhanda, L. 1984. Bonsai culture. Ornamental Horticulture in problem. 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